Internal combustion engines may generate blow-by gases during operation. That is to say that gases generated in the combustion chamber may leak past the piston rings and into the crankcase. As a result, oil degradation as well as other types of engine degradation may occur when blow by gases are not vented from a sealed crankcase. Therefore, draft tubes extending from the crankcase to the bottom of the engine compartment were developed to vent the blow-by gas from the crankcase to the atmosphere. Draft tubes rely on the motion of the vehicle to generate a vacuum to generate blow-by gas flow from the crankcase to the atmosphere. However, draft tubes may release hydrocarbons to the atmosphere. Furthermore, vehicle motion is required to operate the draft tube, thereby decreasing the window of operation for the draft tubes. Moreover, draft tubes may also take on water in certain driving environments. As a result, engine degradation may occur.
To solve at least some of the aforementioned shortcomings of the draft tube, positive crankcase ventilation (PCV) systems have been developed. For example, U.S. Pat. No. 4,790,287 describes a crankcase ventilation system for an engine. Air is flowed through openings in a valley between opposing cylinders in a V configuration engine to a PCV valve that is in fluid communication with an engine air intake system. In this way, gas flow through the crankcase may be directed to the engine air intake system for combustion, thereby decreasing vehicle emissions. The crankcase ventilation system further includes an oil separator for separating oil from the air in the crankcase ventilation system. Thus, the air flowing out of the crankcase ventilation system may not be entrained with oil from the engine.
The Inventors have recognized several drawbacks with this type of positive crankcase ventilation system. Firstly, due to the geometric configuration of the inlet and outlet crankcase ventilation conduits, an airflow pattern may develop which may decrease the ability of the ventilation system to remove water vapor from the crankcase as well as reduce oil degradation. Specifically, air may not flow to certain areas of the crankcase such as locations in the front and rear of the crankcase, therefore oil degradation (e.g., oil gelling) may occur in the aforementioned locations.